In recent years, percutaneous absorption-type pharmaceutical preparations have actively been developed as a means of administering a drug through the surface of skin into the living body for the purpose of prolongation of the expression of pharmacological effects or reduction of the side effect. In particular, an adhesive plaster has attracted a great deal of attention in easiness of handling and the strict dose.
In such an adhesive plaster, a variety of ideas have been attempted to the drug-containing layers, and improvement of its transdermal property or immediate action as well as prolongation of the action have been studied from several view points.
As for the support of adhesive plasters, because they have to be applied to the skin surface, easiness of handling at the application, mobility (flexibility) responding to movement of the skin surface, no irritation to the skin, and so on, are required as important characters. In addition, it is also required to prevent reduction of the drug content due to shift of the drug to the support. In order to respond to such requirement, a laminated film prepared by gluing a plastic film onto a porous material via an adhesive (Patent Document 1: JP-A-5-309772), and a percutaneous absorption-type pharmaceutical preparation which is prepared by laminating a plaster layer on the surface of polyester film as support prepared by laminating a soft auto-foam onto a polyester film, have been proposed (Patent Document 2: JP-A-6-30983).
The so far proposed percutaneous absorption-type pharmaceutical preparations, however, have a problem that a sublimation drug contained in the plaster layer is released as volatile substance from the edge portion of the preparation with a lapse of time. The released drug is adsorbed in the adhesives contained in a support layer to cause plasticization of the adhesives, thereby decreasing the laminate strength between plastic films such as porous materials; thus, when the preparation is applied to or peeled off from the skin surface, in some cases a nonwoven fabric only is peeled off, leaving the plaster layer on the skin surface. In addition, the content of the drug to be contained in the plaster decreases due to release of the drug. Therefore, in a case of a sublimation drug being contained, a percutaneous absorption-type pharmaceutical preparation which is not accompanied by the above-mentioned problems has been desired.